During 2 to 3 September 2017, the Sydney region experienced reduced visibility and exceedances of the daily PM2.5 national benchmark at 6 monitoring stations. This was due to smoke from hazard reduction burns (HRBs) undertaken in the north and west of the Sydney basin.
During this period, there was a high-pressure system over the east coast of Australia creating strong temperature inversion and calm atmospheric conditions, which brought light north-westerly air flows into Sydney region. Smoke from the HRBs was transported across the basin to impact Sydney city, which experienced reduced visibility and elevated PM2.5 levels. The afternoon north-easterly sea breeze blocked the dispersion of smoke, causing additional build-up and exceedances of daily PM2.5 national benchmark across Sydney. Smoke continued to elevate the PM2.5 levels, particularly closer to the HRBs near western Sydney, until the passage of a cold front with stronger south-westerly assisted smoke dispersion.
The results from this episode analysis are useful for understanding HRB-related fine particle (PM2.5) pollution in Sydney.
